package com.flyduck.common.util;

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * @author flyduck
 */
public class RSAUtil {

    private static final String PRIVATE_KEY = "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";
    private static final String PUBLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCO9jVglrprLeNTGgRKeSbqmuNpbdAcf6dOjPsWgTwcby4ukCnR03KklthEfLvvvweF3k65id78XIftJMaLX6Uem3ZuNOTTAjZLXMaGu5BoGJ/cuILC3SDLsuKKBw0bzMklz2pSA9dd1jJDGWYb3Iw1kH3exl6R9XMkmhB5BQCixwIDAQAB";

    private static Map<Integer, String> keyMap = new HashMap<Integer, String>();  //用于封装随机产生的公钥与私钥

    public static void main(String[] args) throws Exception {
        //生成公钥和私钥
        genKeyPair();
        //加密字符串
        String message = "df723820";
        String publicKey = keyMap.get(0);
        String privateKey = keyMap.get(1);
        System.out.println("随机生成的公钥为(" + publicKey.length() + "):" + publicKey);
        System.out.println("随机生成的私钥为(" + privateKey.length() + "):" + privateKey);
        String originPassword = "admin";
        System.out.println("加密前:"+originPassword);
        String encrypt = encrypt(originPassword);
        System.out.println("加密后:"+encrypt);
        String decrypt = decrypt(encrypt);
        System.out.println("解密后:"+decrypt);

    }

    /**
     * 随机生成密钥对
     *
     * @throws NoSuchAlgorithmException
     */
    public static Map<Integer, String> genKeyPair() throws NoSuchAlgorithmException {
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器，密钥大小为96-1024位
        keyPairGen.initialize(1024, new SecureRandom());
        // 生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥
        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
        // 得到私钥字符串
        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
        // 将公钥和私钥保存到Map
        keyMap.put(0, publicKeyString);  //0表示公钥
        keyMap.put(1, privateKeyString);  //1表示私钥
        return keyMap;
    }

    /**
     * RSA公钥加密
     *
     * @param str       加密字符串
     * @return 密文
     * @throws Exception 加密过程中的异常信息
     */
    public static String encrypt(String str) {
        //base64编码的公钥
        byte[] decoded = Base64.decodeBase64(PUBLIC_KEY);
        String outStr = null;
        try {
            RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
            //RSA加密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, pubKey);
            outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        } catch (Exception e) {
            throw new RuntimeException("RSA公钥加密失败！",e);
        }
        return outStr;
    }

    /**
     * RSA私钥解密
     *
     * @param str        加密字符串
     * @return 铭文
     * @throws Exception 解密过程中的异常信息
     */
    public static String decrypt(String str) {
        //64位解码加密后的字符串
        String outStr = null;
        try {
            byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
            //base64编码的私钥
            byte[] decoded = Base64.decodeBase64(PRIVATE_KEY);
            RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
            //RSA解密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, priKey);
            outStr = new String(cipher.doFinal(inputByte));
        } catch (Exception e) {
            throw new RuntimeException("RSA私钥解密！",e);
        }
        return outStr;
    }

    /**
     * 是否一致
     * @param password
     * @param cryptPassword
     * @return
     * @throws Exception
     */
    public static Boolean check(String password,String cryptPassword) {
        return password.equals(decrypt(cryptPassword));
    }
}
